Update from https://crrev.com/316786

net/quic/crypto/null_decrypter.cc

Index: net/quic/crypto/null_decrypter.cc
diff --git a/net/quic/crypto/null_decrypter.cc b/net/quic/crypto/null_decrypter.cc
index 4411b7c0ba1fe460a51f82bf05933041c4c02b7c..8a18172a5c299ded7443f1cbfae583fe8fbd18e2 100644
--- a/net/quic/crypto/null_decrypter.cc
+++ b/net/quic/crypto/null_decrypter.cc
@@ -19,28 +19,31 @@ bool NullDecrypter::SetNoncePrefix(StringPiece nonce_prefix) {
   return nonce_prefix.empty();
 }
 
-QuicData* NullDecrypter::DecryptPacket(QuicPacketSequenceNumber /*seq_number*/,
-                                       StringPiece associated_data,
-                                       StringPiece ciphertext) {
-  // It's worth duplicating |Decrypt|, above, in order to save a copy by using
-  // the shared-data QuicData constructor directly.
+bool NullDecrypter::DecryptPacket(QuicPacketSequenceNumber /*seq_number*/,
+                                  const StringPiece& associated_data,
+                                  const StringPiece& ciphertext,
+                                  char* output,
+                                  size_t* output_length,
+                                  size_t max_output_length) {
   QuicDataReader reader(ciphertext.data(), ciphertext.length());
-
   uint128 hash;
+
   if (!ReadHash(&reader, &hash)) {
-    return nullptr;
+    return false;
   }
 
   StringPiece plaintext = reader.ReadRemainingPayload();
-
-  // TODO(rch): avoid buffer copy here
-  string buffer = associated_data.as_string();
-  plaintext.AppendToString(&buffer);
-
-  if (hash != ComputeHash(buffer)) {
-    return nullptr;
+  if (plaintext.length() > max_output_length) {
+    LOG(DFATAL) << "Output buffer must be larger than the plaintext.";
+    return false;
+  }
+  if (hash != ComputeHash(associated_data, plaintext)) {
+    return false;
   }
-  return new QuicData(plaintext.data(), plaintext.length());
+  // Copy the plaintext to output.
+  memcpy(output, plaintext.data(), plaintext.length());
+  *output_length = plaintext.length();
+  return true;
 }
 
 StringPiece NullDecrypter::GetKey() const { return StringPiece(); }
@@ -60,8 +63,10 @@ bool NullDecrypter::ReadHash(QuicDataReader* reader, uint128* hash) {
   return true;
 }
 
-uint128 NullDecrypter::ComputeHash(const string& data) const {
-  uint128 correct_hash = QuicUtils::FNV1a_128_Hash(data.data(), data.length());
+uint128 NullDecrypter::ComputeHash(const StringPiece& data1,
+                                   const StringPiece& data2) const {
+  uint128 correct_hash = QuicUtils::FNV1a_128_Hash_Two(
+      data1.data(), data1.length(), data2.data(), data2.length());
   uint128 mask(GG_UINT64_C(0x0), GG_UINT64_C(0xffffffff));
   mask <<= 96;
   correct_hash &= ~mask;